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Abstract

Populations of arboricolous oribatids mites (Acari: Oribatida) were studied in two inundation forests (varzea and igapo) particularly their reactions to the effects of the flood cycle and abiotic factors. Representative species of trees typical for each forest type were chosen for monthly collections using the Bark-brushing Method. Differences were found between the arboricolous fauna of the two forests. The ecological indices, density and the species diversity of the arboricolous fauna, were low in the varzea in comparison to the igapo. Distinct differences were observed in the two areas with respect to dominant groups. The data indicate that the varzea is more subject to perturbation by both, environmental pressure and human intervention, than the igapo. The reactions of the oribatid mites fauna was more related with the absence of food during the terricolous phase caused by the long period of submersion of the trunks, than with the flood cycle.